This invention relates to a stretching and moulding machine for the production of both soft and hard pasta filata cheese, such as mozzarella, provolone and the like.
In the production of pasta filata cheese, curds are made plastic by mixing them with hot water, having a temperature in the range 70.degree. to 90.degree. C., and then kneading or stretching the mix to obtain the so-called "pasta filata". The chemio-physical action of hot water and the mechanical action of stretching together induce a structural transformation of the casein molecule, giving the pasta filata peculiar properties of stringiness that typify this kind of products. The pasta filata thus obtained is then moulded into desired shapes, either by manual shaping or by pouring into moulds.
The processing of pasta filata, which used to be done in the past by stirring curds and hot water manually with a kneading paddle in open vats, has more recently been mechanized. Continuous auger stretching machines came into general use and, more recently, continuous stretching machines having reciprocating plunger arms, as known from U.S. Pat. No. 4,182,232.
While stretching machines according to said U.S. patent have the ability to effectively simulate manual stretching, by pulling pasta filata apart and thus producing a satisfactory "soft" pasta filata, having a high water content, as required for Italian mozzarella, bocconcino, and the like, their mechanism is complex, bulky and expensive to manufacture. Also, such prior machines are difficult to clean, because they include tunnels or chambers that are not readily accessible.
Further, while prior machines using stretching augers are suitable for "hard" cheese such as provolone, they are unsuitable for soft cheese, because they squeeze the product, thus tending to expel water from it. On the other hand, machines using reciprocating plunging arms according to said U.S. patent are only suitable for soft pasta filata, and cannot be satisfactorily employed in the production of hard cheeses.